Become robust to things being removed from typing (#595)

JelleZijlstra · web-flow · commit d90a2f402e52 · 2025-05-10T07:33:04.000-07:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,8 @@
 # Unreleased
 
 - Drop support for Python 3.8 (including PyPy-3.8). Patch by [Victorien Plot](https://github.com/Viicos).
+- Do not attempt to re-export names that have been removed from `typing`,
+  anticipating the removal of `typing.no_type_check_decorator` in Python 3.15.
 
 New features:
 
diff --git a/pyproject.toml b/pyproject.toml
@@ -94,6 +94,9 @@ ignore = [
     "RUF012",
     "RUF022",
     "RUF023",
+    # Ruff doesn't understand the globals() assignment; we test __all__
+    # directly in test_all_names_in___all__.
+    "F822",
 ]
 
 [tool.ruff.lint.per-file-ignores]
diff --git a/src/test_typing_extensions.py b/src/test_typing_extensions.py
@@ -6827,6 +6827,15 @@ def test_typing_extensions_defers_when_possible(self):
                     getattr(typing_extensions, item),
                     getattr(typing, item))
 
+    def test_alias_names_still_exist(self):
+        for name in typing_extensions._typing_names:
+            # If this fails, change _typing_names to conditionally add the name
+            # depending on the Python version.
+            self.assertTrue(
+                hasattr(typing_extensions, name),
+                f"{name} no longer exists in typing",
+            )
+
     def test_typing_extensions_compiles_with_opt(self):
         file_path = typing_extensions.__file__
         try:
diff --git a/src/typing_extensions.py b/src/typing_extensions.py
@@ -4223,46 +4223,52 @@ def evaluate_forward_ref(
 
 
 # Aliases for items that are in typing in all supported versions.
-# Explicitly assign these (rather than using `from typing import *` at the top),
-# so that we get a CI error if one of these is deleted from typing.py
-# in a future version of Python
-AbstractSet = typing.AbstractSet
-Annotated = typing.Annotated
-AnyStr = typing.AnyStr
-BinaryIO = typing.BinaryIO
-Callable = typing.Callable
-Collection = typing.Collection
-Container = typing.Container
-Dict = typing.Dict
-ForwardRef = typing.ForwardRef
-FrozenSet = typing.FrozenSet
+# We use hasattr() checks so this library will continue to import on
+# future versions of Python that may remove these names.
+_typing_names = [
+    "AbstractSet",
+    "AnyStr",
+    "BinaryIO",
+    "Callable",
+    "Collection",
+    "Container",
+    "Dict",
+    "FrozenSet",
+    "Hashable",
+    "IO",
+    "ItemsView",
+    "Iterable",
+    "Iterator",
+    "KeysView",
+    "List",
+    "Mapping",
+    "MappingView",
+    "Match",
+    "MutableMapping",
+    "MutableSequence",
+    "MutableSet",
+    "Optional",
+    "Pattern",
+    "Reversible",
+    "Sequence",
+    "Set",
+    "Sized",
+    "TextIO",
+    "Tuple",
+    "Union",
+    "ValuesView",
+    "cast",
+    "no_type_check",
+    "no_type_check_decorator",
+    # This is private, but it was defined by typing_extensions for a long time
+    # and some users rely on it.
+    "_AnnotatedAlias",
+]
+globals().update(
+    {name: getattr(typing, name) for name in _typing_names if hasattr(typing, name)}
+)
+# These are defined unconditionally because they are used in
+# typing-extensions itself.
 Generic = typing.Generic
-Hashable = typing.Hashable
-IO = typing.IO
-ItemsView = typing.ItemsView
-Iterable = typing.Iterable
-Iterator = typing.Iterator
-KeysView = typing.KeysView
-List = typing.List
-Mapping = typing.Mapping
-MappingView = typing.MappingView
-Match = typing.Match
-MutableMapping = typing.MutableMapping
-MutableSequence = typing.MutableSequence
-MutableSet = typing.MutableSet
-Optional = typing.Optional
-Pattern = typing.Pattern
-Reversible = typing.Reversible
-Sequence = typing.Sequence
-Set = typing.Set
-Sized = typing.Sized
-TextIO = typing.TextIO
-Tuple = typing.Tuple
-Union = typing.Union
-ValuesView = typing.ValuesView
-cast = typing.cast
-no_type_check = typing.no_type_check
-no_type_check_decorator = typing.no_type_check_decorator
-# This is private, but it was defined by typing_extensions for a long time
-# and some users rely on it.
-_AnnotatedAlias = typing._AnnotatedAlias
+ForwardRef = typing.ForwardRef
+Annotated = typing.Annotated

Original file line number	Diff line number	Diff line change
`@@ -94,6 +94,9 @@ ignore = [`
`94`	`94`	`"RUF012",`
`95`	`95`	`"RUF022",`
`96`	`96`	`"RUF023",`
	`97`	`+ # Ruff doesn't understand the globals() assignment; we test __all__`
	`98`	`+ # directly in test_all_names_in___all__.`
	`99`	`+ "F822",`
`97`	`100`	`]`
`98`	`101`
`99`	`102`	`[tool.ruff.lint.per-file-ignores]`